Alan Turning was a British mathematician and cryptanalyst. He is considered by many to be the father of computer science and artificial intelligence. His 100th birthday is the 23rd of June in 2012.

Alan Turing was prosecuted by the British goverment in 1952. Why? For being homosexual at a time when homosexual acts were illegal in the UK. He accepted chemical castration, being treated with female hormones, instead of prison and died in 1954.

In 2009, Gordon Brown (the Prime Minister at the time), made a public apology for the way Turing was treated but just this year the UK government rejected a pardon for the genius.

**What did Alan Turing invent? **

Turing worked in Hut 8, a secret unit in Bletchley Park during World War II, cracking codes. Projects included bombe; a machine that could help program the Enigma machine.

He is, perhaps, most well known for the Turing machine. The Turing machine is a device that moves symbols on a strip of tape depending on a table of rules. This allows the machine to process logical instructions – the basis of any computer algorith.

Google’s doodle of 2012 pays homage to Turing. It is Alan Turing’s 100th birthday machine.

**How do you use Google’s Alan Turing doodle?**

The goal is to match binary number shown in the large bar, below the shaded-out Google, with the binary digit in the small bar beside it. As you match the numbers the Google logo fills with colour.

The machine runs from left to right and reacts to each button instruction. The arrows move the machine’s focus either to the right or left. The squares are triggered if the reader matches the number in the square and responds by moving down the row. The circle arrows denote repeats and the connecting pipe shows where the machine will return to for the repeat.

In this example we see the first three instructions are “If the reader says 1 then go down to the track below”, the next top instruction is move one to the left, there’s then a repeat that loops back four times. The track below, if you start from the far left, sets a zero and then moves the reader along to the right three times.

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